Television system



`une 1, 1.937. A. v. BEDFORD 2,082,093

TELEVISION SYSTEM .June 1, 1937. A. v. BEDFORU 032,993

TELEVISION SYSTEM Filed Jan. 28, 1953 2 Sheets-Sheet 2 Patented June l,'1937 mural) STATES PATENT OFFICE Application January 2B, 1933, Serial120,653,941

20 (Halma.

My invention relates to improvements in television systems.

For the purpose of eliminating dicker of the reproduced picture in atelevision receiver, it has been found expedient to double the usualnumber of frames scanned per second and, in the scanning action, tointermesh the lines of the odd pictures, for example, with the lines oithe even pictures. A receiver of this type is disclosed in detail in thecopending application by Randall C. Ballard, filed July 19, 1932 andbearing Serial No. 623,325. By following this method of socalledintermeshed or interlaced scanning, it becomes practical to make thenumber of frames per second as high as sixty. With the' number of framesper second at sixty, the common alternating current power circuits at 60cycles can be used to advantage for synchronizing or control purposes. Aproblem arises, however, when the subject ior transmission is a standardmoving-picture iilm moved intermittently at the usual rate oitwenty-four frames a second.

With the foregoing in mind, it is one oi the objects of my invention toprovide an improved television system and method of operation thereofwhereby all the advantages of use of common alternating current at sixtycycles and the use of a standard moving-picture lm for twentyfour framesa second, can be obtained.

Other objects and advantages will hereinafter appear.

In accordance with my invention, different views of a moving subject areexposed to the transmitting apparatus for transmission, and picturesignals of each of certain complete views are developed at least twicein succession.

More particularly, in accordance with my in' vention, the scanningaction at the transmitter isv made to take place at the rate of sixtyframes a second, the individual views are presented for scanning at therate of twenty-four a second, and every other view is scanned twice insuccession while each of the other views is scanned three times insuccession.

Further, in accordance with my invention, a cathode ray tube is causedto scan screen structure at the rate of sixty frames a second. For thepurpose of developing picture signals, a moving picture film which isthe subject for transmission is moved intermittently. An image of eachof the odd pictures, for example, is projected twice in succession ontothe screen structure, and an image of each of the even pictures isprojected three times in succession onto the screen structrue, allduring stationary periods of the film.

The timing is such that the cathode ray scans Athe screen structure onlyduring the periods between those during which the illm is stationary.

My invention resides in the improved system, apparatus and method ofoperation of the character Ahereinafter described and claimed.

For the purpose of illustrating my invention, an embodiment thereof isshown in the drawings, wherein Figure 1 is a simplied elevational view,partly diagrammatic, of a television transmitting system constructed andoperating in accordance with my invention;

Figs. 2, 3, and 4 are enlarged elevational views, looking from the rearof the apparatus shown in Fig. l, and illustrating a step in theoperation;

Fig.` 5 is an elevational view of one of the parts, looking toward theleft in Fig. 1;

Fig. 6 is a picture chart, illustrative of the manner of operation inFig. 1; and

Fig. 7 is an enlarged fragmentary view, taken from Fig. 5.

With reference to Fig. 1, the reference numeral l0 designates a cathoderay tube for developing picture signals. This tube comprises a suitablephotosensitive, mosaic screen structure I2 which, for example, may bemade up of a great number of minute, photosensitive silver globulessupported on a metallic base plate and each insulated from the latterand from each other. A suitable electron gun I4 operates to develop aray I6 of electrons and to direct the same at the screen structure. Thetube is provided with a grounded anode in the form of a silver coatingl1 'on the inside surface.

The ray I6 is caused to scan the screen structure during intermittentperiods. During the relatively short periods between the intermittentscanning periods, the ray is returned to the initial starting point forthe next succeeding scanning action. During each scanning period, theray scans the screen along a saw-tooth path. l Let it be assumed, forexample, that there are to be 60 pictures or frames a second, eachhaving 1211/2 lines horizontally, the horizontal lines of the odd framesbeing intermeshed with or falling between those of the even frames. Forthese conditions, the ray is deflected horizontally by coils I8 throughwhich a saw-tooth current wave is caused to pass at a frequency of 7290cycles.

A suitable generator 20 supplies the current wave for this purpose.Also, the ray is deiiected vertically by coils 22 through which asaw-tooth current wave is caused to pass at a frequency of 60 cycles. Asuitable generator 24 supplies the 60- cycle current wave for thispurpose.

The electron gun I4 is provided with a control electrode or grid 26 bywhich the intensity of the ray is varied in the manner and for thepurpose hereinafter explained.

The object for transmission is a standard motion picture film 28 movedintermittently, at the rate of 24 pictures a second, by an intermittentfeed device 88. The camshaft 32 of the intermittent device is drivendirectly from the shaft 34 of a motor 36. The shaft 34 rotates uniformlyat the rate of 30 revolutions a second, and the driving connection tothe camshaft 32 is of any suitable type having a drive ratio of 1 to21/2. The camshaft 32, therefore, makes twelvecomplete revolutions eachsecond.

A shutter disc 38 is fixed on the motor shaft and is provided with twodiametrically opposite openings 48 and 42, each of which, at its widestpoint, extends along one-twentieth of the circumference. The individualpictures of the film are projected onto the screen structure I2 throughthese openings.

The shutter openings 48 and 42 are given the characteristic shape, asshown in Fig. 5, for the purpose of permitting the maximum amount oflight to pass through to the screen I2.

'I'he intermittent device 38 is provided with two cams, 44 and 46, eachof which is effective to rotate the shaft 48 of the film-drivingsprocket 58 through ninety degrees. This is illustrated in Figs. 2, 3,and 4. In Fig. 2, the cam surface 52 is about to engage the pin 54 toimpart counterclockwise movement to the shaft 48. As the shaft 32continues to rotate, the cam surface 56 engages the pin 58, as shown inFig. 3, to continue rotation of the shaft 48 to the position shown inFig. 4. The shaft 48 is thereby moved through ninety degrees, from theposition shown in Fig. 2 to that shown in Fig. 4.

An important characteristic of the intermittent device 88 resides in thefact that the axis of the cam 44 is displaced less than one-hundred andeighty degrees from the axis of the cam 46, the actual displacementbeing one-hundred and forty-four degrees, as shown. Considering theaction for each complete revolution of the shaft 32, and with referenceto Fig. 6, the pictures moved into position by the cam 44 are stationaryduring the two periods AB and CD, while the pictures moved into positionby the cam 46 are stationary during the three periods EF, GH and IJ. Inother words, we will say that for each revolution of the shaft 32, thereis one odd and one even picture of the film moved into position, andthat each even picture is allowed to remain stationary for a 50 per centlonger period than the stationary period for the odd picture. The reasonfor this will hereinafter appear.

The drive ratio of l to 21/2` between the shafts 82 and 34 provides thatfor every 30 revolutions of the shutter disc 38, the shaft 48 of thefilmdrivlng sprocket 58 will be rotated through ninety degreestwenty-four times to impart an intermittent movement to the film 28 atthe rate of 24 pictures a second.

The disposition of the shutter openings 48 and 42 and the fixedadjustment between the shafts 82 and 34 are such that the relativelyshort periods, during which pictures are flashed onto the screen I2,occur during the periods when the pictures are stationary. This isrepresented in Fig. 6. `With the disc 38 rotating at the rate of 30revolutions a second, therefore, images of the individual nlm picturesare dashed on to the screen I2 at the rate of sixty frames a second.Also, on account of the characteristic construction of the intermittentdevice I8 and the timing, as explained, there will be two images of eachof the odd pictures flashed onto the screen I2 in succession, and threeimages of each of the even pictures flashed onto the screen insuccession.

For the purpose of maintaining operation of the generators 28 and 24 atthe respective frequencies of 7290 cycles and 60 cycles, sharpelectrical impulses 68 of a given amplitude are developed at thefrequency of '7290 cycles and, after passing through a suitableamplifier 62 are supplied to the generator 28 and operate to drive thesame at this frequency. Also, electrical impulses 64 are developed ofgreater duration than the horizontal impulses, and at the frequency of60 cycles. These are also amplified in the amplifier 62, and are thensupplied to the generator 24 to drive the same at the required frequencyof 60 cycles. The adjustment of the generator 24 is such that it 'doesnot respond to the impulses 88 for horizontalsynchronizing.

For the purpose of developing the synchronizing impulses 68, the disc 88is provided with 243 apertures 66, evenly spaced and disposed on thecircumference of a circle concentric with the axis of the shaft 34.During each revolution of the disc 38, light from a suitable source 68passes through these apertures to a photoelectric cell 18 connected tothe input circuit of the amplifier 62, thereby developing the sharpimpulses 68 for maintaining horizontal defiection of the ray I6 at therate of 7290 deflections a second. The amplified impulses are suppliedto the geneator 28 through a suitable connection, as indicated.

Several of the apertures 66 are cut through to provide two elongatedapertures 12 and 14, diametrically opposite to each other, and each ofthe same length. With the disc 38 rotating at the rate of 30 revolutionsa second, the longer apertures 12 and 14 admit light to the photocell 18for a longer period than each of the apertures 66 to develop the framingimpulses 64 at the required frequency of 60 cycles for maintainingvertical deflection of the ray I6 at this frequency. These impulses arealso amplified in the amplifier 62 and then supplied to the generator 24through a suitable connection, as shown. The disposition of the framingapertures 12 and 14 is such that the same start to admit light to thecell 18 at substantially the same instant that the respective shutteropenings 48 and 42 start to admit light to the screen I2.

For the purpose of causing the ray I6 to scan the screen I2 first alongspaced horizontal lines for any given odd frame and then, for thefollowing even frame, along horizontal lines between those of thepreceding odd frame, the framing aperture 12, for example, is made byremoving all of the material of the disc between one of the apertures 66and each of the adjacent apertures. This is shown more clearly in Fig.7. Since, however, there are 243 of the apertures 66, and the framingaperture 14 is of the same length and diametrically opposite to theaperture 12, the ends of the aperture 14 will fall between adjacentapertures 66. This is also shown more clearly in Fig. 7. The action,therefore, is as follows: Looking toward the right in Fig. l, the ray I6starts at the upper left-hand corner of the screen I2 and scans the samealong 1191/2 lines for an odd frame, after which a framing impulse 64occurs to start return deflection of the ray vertically. Assuming thatreturn deflecpoint B. the

tion vertically occupies the period for two full deflectionshorizontally, when the ray starts to scan the screen for the succeedingeven frame, it will have been deflected horizontally 1211/2 times andwill be directed at the center of the upper horizontal edge of thescreen and slightly above horizontal line #1. During the next 1191/2horizontal deflections, for the succeeding even frame, therefore, theray will scan the screen I2 along horizontal lines between or displacedfrom those of the preceding odd frame, and at the end of the 241stdeflection will be directed at the lower right-hand corner of thescreen. At this time, another framing impulse B4' occurs to start returndeflection of the ray vertically. This return deflection, as' before,occupiesthe period for two full deflections horizontally, so that whenthe ray is directed at the upper left-hand corner of the screen, it willhave been deflected horizontally exactly 243 times. For convenience, ithas been stated previously that each frame compirses 1211/2 horizontallines, but from the foregoing it will be understood that each frameloses two lines because it has been assumed that the period of two lineselapses during each return deflection vertically.

It will be understood that picture signals are only developed as the rayis deilected horizontally from left to right and vertically from top tobottom. During return deflection of the ray from right to left,horizontally, and also during return deflection of the ray vertically,the ray serves no useful purpose in the way of developing picturesignals. It is, therefore, desirable to out off the ray during returndeflection thereof in both horizontal and vertical directions, and forthis purpose the synchronizing and framing impulses are taken from asuitable stage of the amplifier 62 and applied by a connection 16 to thecontrol grid 26. The polarity and amplitude of each of these impulses issuch as to impart a negative bias to the grid 26 which is effective tocut off the ray so that it will be non-effective with respect to thescreen I2.

The operation of my improved system will now be further explained, withreference to Fig. 6, which is a chart representative of the entireoperating action for each complete revolution of the shaft 32. From thepoint A clockwise to the point B, the opening 4D is in position topermit an image of an odd film picture (picture #1) to be projected ontothe screen I2. During this period, also, the elongated aperture 'I4 iseffective to develop a framing impulse 64 which drives the generator 24to effect return deflection vertically of the ray, and, at the sametime, to impart a negative bias to the grid 2B to cut off the ray duringthe return deflection thereof. At the shutter 32 cuts off all light tothe screen i2. At this point, the negative bias on the grid 2B will havebeen removed to restore the ray to normal intensity. Also, deflection ofthe ray for scanning the screen begins, and occupies a period from pointB clockwise to the point C. During the scanning period, therefore, thescreen I2 is dark. At the point C, the opening 42 is in position topermit a second image of picture #l to be projected onto the screen I2.During this period, the elongated aperture 12 is effective to developanother framing impulse B4 which again drives the generator 24 to effectreturn deflection vertically of the ray, and, at the same time,

to impart a negative bias to the grid 26 to cut oi the ray during thisreturn deflection thereof. At the point D, the shutter cuts off alllight to the screen I2. At this point, the negative bias on the grid 26will have been removed to restore the ray to normal intensity. Also,deflection of the ray for scanning picture #l the second time begins,and occupies a period from the point D clockwise to the point E. Duringthe period D to E, therefore, the screen is dark. At the point D, thecam 46 starts to move the next and even picture (picture #2) intoposition, and completes this movement at the point E. At the completionof the scanning action, at the point E, the ray is again cut off by theaction of the aperture 14, and the shutter opening 40 starts to admitlight to the screen I2. From the point E to the point F, an image of thepicture #2 is flashed onto the screen I2 through the opening l0. Theoperating action then continues as above with the following exception.On account of the characteristic construction of the intermittent device30, picture #2 is permitted to remain stationary from thc point F to thepoint G. The screen is dark from the point F to the point G, duringwhich period the screen is scann-ed. During the period G to H, the rayis cut 01T and a second image of picture #2 is flashed onto the screenI2 through the opening 42. During the period H to I, the screen is darkand is again scanned by the ray I6. During the period I to J, the ray iscut off and a third image of picture #2 is flashed onto the screen I2through the opening 40. At the point J, the cam 44 starts to move thenext odd picture (picture #3) into position. During the period J to thescreen is dark and is scanned by the ray I6. At the point A, the cycleof one complete revolution of the shaft 32 is completed. At this point,the ray is cut off, and from the period A to B, an image of picture #3is flashed onto the screen I2 through the opening 42. The action thencontinues as before.

With regard to the operating action which takes place in developingpicture signals, it will be understood that when an image of a pictureis flashed onto the screen during each of the relatively short periodsAB', CD, EF, GH and IJ, electrostatic charges are stored on the screen,the value of the stored charge at the particular area of the screenbeing proportional to the value of light intensity at the correspondingelemental These signals are supplied by way of a connection 'il to asuitable amplifier 18. The amplified synchronizing impulses are alsoSupplied to this amplifier from the amplifier B2, as indicated, and arethen passed with the amplified picture signals to a suitable radiotransmitter 20.

From the foregoing, it will be seen that by my improved system andmethod of operation, it is possible to take advantage of the use of thecommon alternating current supply at 60 cycles for synchronizing orcontrol purposes, and to accommodate the transmitter under theseconditions for standard moving-picture film as the subject fortransmission and which is fed intermittently through the apparatus atthe rate of 24 frames a second, or, at least, at a rate different thanthe scanning rate in terms of frames per second.

Another important advantage in my improved system and method ofoperation, whereby it is feasible to use alternating current supply at6J cycles, resides in the fact that both the respective frequencies forvertical and horizontal deflection of the ray are even multiples of thesupply frequency of 60 cycles. Hence, all disturbances resulting fromimperfect iiltering of the amplier voltage supplies at the transmittingand receiving stations are stationary with respect to the reproducedpicture and are, therefore, less objectionable than would otherwise bethe case.

I believe myself to be the iirst to provide a television transmittingsystem of the character described wherein the individual views are pre-`sented for transmission at a rate different than the scanning rate interms of frames per second, and wherein, in order to allow for this,certain of the views are scanned m times, while other views. occurringbetween said certain views are scanned n times, m and n being wholenumbers and one oi these numbers being greater than the other.

While but one embodiment of my invention has been disclosed, it is seenthat modifications, within the conception of those skilled in the art,are possible without departing from the spirit of my invention or thescope of the claims.

I claim as my invention:

1. 'Ihe method of operating a television transmitter including a cathoderay transmitter tube having a light-sensitive screen which comprisesprojecting different succeeding views of a subject to be transmittedupon said screen, scanning each of the alternate views projected on saidscreen m times in succession with said cathode ray to develop picturesignals, and scanning each of the other views projected on said screen ntimes in succession with said cathode ray to develop picture signals,wherein m and n are whole numbers and wherein one number is greater than'the other, the time required for m plus n scannings being equal to thetime required for projecting a whole number of picture frames upon saidscreen.

2. 'I'he method of operating a television trans- 'mitter including thecathode ray transmitter tube having a light-sensitive screen whichcomprises projecting different succeeding views of a subject to betransmitted upon said screen, scanning alternate views projected on saidscreen twice in succession with said cathode ray to develop picturesignals. and scanning the other views projected on said screen threetimes in succession with said cathode ray to develop picture signals.

3. The method of operating a television transmitter including a cathoderay transmitter tube having'a light-sensitive screen which comprisesscanning said screen with said cathode ray at the rate of 60 completescannings per second, moving individual views into position forprojection upon said screen at the rate of 24 per second, projecting thealternate views upon said screen twice in succession and in such timerelation with respect to said scanning that said alternate views arescanned twice on said screen to develop plcture signals, and projectingthe other views upon said screen three times in succession and in suchtime relation to said scanning that said other views are scanned threetimes each to develop picture signals.

4. The method of operating a television transmitter including anintermittent device for moving a motion picture iilm into position forscanning which comprises moving one picture frame of said film intoposition for scanning, scanning said picture frame m times in successionto develop picture signals, moving the next picture frame into positionfor scanning, and scanning said next picture frame n times in successionto develop picture signals, wherein m and n are whole numbers andwherein one number is greater than the other, the time required for mplus n scannings being equal to the time required for projecting a wholenumber of picture frames upon said screen, and repeating said operationfor succeeding picture frames'.

5. The method of transmitting a television picture wherein a movingpicture film is a subject for transmission which comprises imparting in`termittent movement to said nlm at the rate of 24 frames per second andscanning each of said picture frames at the rate of 60 frames per secondin such time relation to said intermittent movement that every otherframe is scanned twice in succession to develop picture signals and eachof the remaining frames is scanned three times in succession -to developpicture signals.

6. The method of operating a television transmitter including a cathoderay transmitter tube having a light-sensitive screen and wherein themoving picture film is a subject for transmission which comprises movingsaid film intermittently at a certain average rate in terms of pictureframes per second into position for projecting said picture frames uponsaid screen, projecting at least twice in succession upon said screenthe same image of each of said picture frames. and scanning said screenwith said cathode ray at a different rate in terms of frames per secondthan said certain average rate where said certain average rate goes intosaid scanning rate a whole number of times plus a fraction and in suchtime relation to the projection of said picture frames upon said screenthat the cathode ray scans in succession complete images of said pictureframes.

7. The method of operating a television transmitter including a cathoderay transmitter tube having a light-sensitive screen and wherein amoving picture Iilm is a subject for transmission which comprises movingsaid film intermittently at a certain rate into position for projectingeach picture frame upon said screen, projecting m times in successionupon said screen the same image of each of alternate picture frames,projecting n times in succession upon said screen the same image of eachof the remaining picture Yframes, wherein m and n are whole numbers andV wherein one number is greater than the other, and scanning said screenby said cathode ray at a rate in terms of picture frames per secondwhich is different than said certain rate and in such time relation thatthe cathode ray scans successively images of complete picture frameswhereby picture signals representative oi complete picture frames aredeveloped for transmission.

8. The method of operating a television transmitter including a cathoderay transmitter tube having a light-sensitive screen and wherein amoving picture iilm is a. subject for transmission which comprisesscanning said screen with said cathode ray during spaced periods of timeand at a given rate in terms of picture frames per second, imparting theintermittent movement to said film at a different rate in terms ofpicture frames per second than said given rate, and projecting upon saidscreen images of certain of the picture frames at least twice. insuccession and only during the space periods of time intervening saidscanning periods and projecting images of picture frames interveningsaid certain picture frames upon said screen' a different number oftimes than said certain picture frames, and maintaining such timerelation between said projections and said scanning that the cathode rayscans images of complete picture frames to produce picture signalsrepresentative of picture frames for transmission.

9. The method of operating a television transmitter including a cathoderay transmitter tube having a light-sensitive screerr and wherein amoving picture film is a subject ior transmission which comprisesscanning said screen with said cathode ray during spaced periods of timeand at the rate of 60 picture frames per second, moving said filmintermittently at the rate of 24 picture frames per second into positionfor projecting each picture frame upon said screen, projecting upon saidscreen the image of every other picture twice in succession and onlyduring the spaced periods of time intervening saidy scanning periods,and projecting the remaining intervening pictures three times insuccession upon said screen and only during the spaced periods of timeintervening said scanning periods.

10. In a television system wherein a movingpicture lm is the subject fortransmission, scanning apparatus for developing picture signals, meansfor moving said lm intermittently into position for scanning eachpicture frame, means including said scanning'apparatus for scanning eachof certain complete picture frames at least twice in succession, andmeans for maintaining said intermittent movement and said scanningaction in such time relation that complete picture frames are scannedsuccessively.

ll. In a television transmitting system, scanning means for developingpicture signals comprising a cathode ray tube provided with screenstructure, means for causing the ray to scan said structure at a givenrate in terms of frames per second, means for supporting amoving-picture film and imparting an intermittent movement thereto at adifferent rate in terms of pictures per second than said given rate,means for projecting onto said structure images of the individual lmpictures and for projecting each of certain of said pictures at leasttwice in succession, and means for maintaining said intermittentmovement and said scanning action in such time relation that completepicture frames are scanned successively.

12. In a television transmitting system, scanning means ior developingpicture signals comprising a cathode ray tube provided withlightsensitive screen structure, means for causing the ray to scan saidstructure at the rate of sixty frames a second, means for supporting amoving-picture ilm and imparting an intermittent movement thereto at therate of twenty-four pictures a second, means for projecting twice insuccession onto said structure an image of every other picture and forprojecting three times in succession onto said structure an image ofeach of the pictures intervening the pictures projected twice, and meansfor maintaining such time relation between said scannings and saidprojections that each picture frame image on said screen is completelyscanned before the next picture frame image is projected on said screen.

13. In a television transmitting system, scanning means for developingpicture signals comprising a cathode ray tubeprovidedwithlight-sensitive screen structure, means for causing the ray to scan saidstructure during spaced periods of time at a given rate in terms offrames per sec- 75 ond, means for supporting a moving-picture nlm andimparting thereto an intermittent movement at a different rate in termsof pictures per second than said given rate, and means cooperating withsaid scanning means for projecting onto said structure images of certainof the pictures at least twice in succession and only during the spacedperiods of time intervening said scanning periods.

14. In a television transmitting system, means for developing picturesignals comprising a cathode ray tube provided with screen structure,means for defiectlng the ray to cause the same to scan said screenstructure during spaced periods of time at a given rate in terms offrames per second and along different sets of parallel lines duringsucceeding frame periods, the lines of one set being disposed betweenuthe lines of another set, means Afor supporting a moving-picture lm andimparting thereto an intermittent movement at a different rate in termsof pictures per second than said given rate, and means cooperating withsaid scanning means for projecting images of certain of the pictureframes at least twice in succession onto said structure and only duringthe spaced periods of time intervening the spaced scanning periods.

15. In a television transmitting system in which a moving-picture filmis the subject for transmission, a cathode ray transmitter tube having alight-sensitive screen, means for moving said lm into positionintermittently for projecting an image of each picture frame upon saidscreen with the intermittent movement such that alternate picture framesof the film remain in position for projection longer than the remainingpicture frames, means for projecting images of each of said alternatepicture frames upon said screen three times in succession with a periodfollowing each projection and for projecting images of each of saidremaining picture frames upon said screen twice in succession with aperiod following each projection, and means for scanning said screenwith said cathode ray during said periods to develop picture signalsrepresentative of said picture frames.

16. In a television transmitting system in which a moving-picture lm isthe subject for transmission, a cathode ray transmitter tube `having alight-sensitive screen, means `for moving said film into positionintermittently at the rate of 2.4 picture frames per second forprojecting an image of each picture frame upon said screen with theintermittent movement such that alternate picture frames of the lrnremain in position for projection longer than the remaining pictureframes, means for projecting images of each of said alternate pictureframes upon said screen three times in succession with a periodfollowing each projection and for projecting images of each of saidremaining picture frames upon said screen twice in succession with aperiod following each projection, and means for scanning said screenwith said cathode ray during said periods to develop picture signalsrepresentative of said picture frames, said scanning being at the rateof 60 picture frames per second.

1'7. In a television transmitting system in which a moving picture nlmhaving picture frames is the subject for transmission, means forintermittently moving said film into position to be scanned at a certainrate in picture frames per second, means for scanning each of certainindividual frames at said rate a predetermined number of times anddeveloping picture signals in accordance with said scanning, and meansfor scanning each oi' said other individual frames located between saidfirst-mentioned individual frames at said rate a different number oftimes and developing picture signals in accordance with said latterscanning.

18. In a television transmitting system in which a moving picture filmhaving picture trames is the subject for transmission, means i'orintermittently moving said lm into position to be scanned with theintermittent movement such that certain individual frames of said iilmremain in position for scanning longer than other individual frames ofsaid iilm located between said iirst-mentioned individual frames, meansfor scanning each of said rst-mentioned individual frames a certainnumber of times and developing picture signals, and means for scanningeach of said other individual frames a smaller number of times anddeveloping picture signals.

19. In a television transmitting system in which a moving-picture filmhaving picture frames is the subject for transmission. means for movingsaid lm into position intermittently for scanning with the intermittentmovement such that alternate picture frames remain in position forscanning longer than the remaining picture frames, means for scanningeach of said alternate frames three times in succession and 0 developingpicture signals in accordance with said scanning, means for scanningeach of the remaining frames two times in succession and developingpicture signals in accordance with said scanning.

20. In a television transmitting system in which a moving-picture nlmhaving picture frames is the subject for transmission. means for movingsaid film into position intermittently for scanning with theintermittent movement such that alternate picture frames remain inposition for scanning for a period which is longer than the period thatthe remaining picture frames are in position for scanning, scanningmeans tor so scanning said frames and simulta neously developing picturesignals that the scanning lines of each complete frame scanning i'allhalf way between the scanning lines o! the preceding complete framescanning, whereby two successive complete scannings produce a full linepicture, and meansior so correlating the action of said ilrst means andsaid scanning means that said alternate frames are scanned three timesin succession and the remaining frames are scanned twice in succession,whereby each of two out of five successive full line pictures consistsof one complete scanning of one frame and one complete scanning of anext adjacent frame.

ALDA V. BEDFORD.

